The invention relates to an operating method for a system used for machining objects by means of laser beams, particularly for a system for boring or structuring printed circuit boards and/or electronic components.
The machining of materials using laser beams has become increasingly important due to the rapid development of laser technology in recent years. In the field of electronic components manufacture in particular the increasing miniaturization of components has made the laser machining of printed circuit boards and substrates as well as electronic components an indispensable tool to allow the micro-structuring of components and substrates required by component miniaturization. For example holes can be bored in substrates with significantly smaller diameters than the diameters of holes bored with conventional drills. Provided that the laser power of the laser beam striking the substrate is known precisely, blind holes can be bored as well as through holes and these are particularly important for multilayer printed circuit boards, with which a number of metal layers are separated from each other in an electrically non-conducting manner by dielectric intermediate layers. Subsequent coating of a blind hole with metal allows different metal layers of the multilayer printed circuit board to be connected together in an electrically conducting manner, so that the integration density on such a multilayer substrate can be increased significantly compared with single-layer or double-layer substrates.
The laser-boring of multilayer substrates is generally effected by means of two different process stages. In the one process stage the metal layers, which generally contain copper or a copper alloy, are removed locally using a laser beam in the ultraviolet spectral range. In the other process stage a dielectric intermediate layer is removed locally using an infrared laser beam, which is generally generated by a CO2 laser. This means that what are known as UV laser machining machines with a laser light source emitting in the ultraviolet spectral range and what are known as IR laser machining machines with a laser light source emitting in the infrared spectral range are used to bore multilayer substrates. If the IR laser machining machines use a CO2 laser to generate the IR laser beam, these are also referred to as CO2 laser machining machines.
A so-called combination laser machining machine is known from U.S. Pat. No. 5,847,960, which contains both a laser emitting in the ultraviolet spectral range and a laser emitting in the infrared spectral range. Combination laser machining machines have the disadvantage that the machining speed is significantly slower with the laser emitting in the ultraviolet spectral range than the machining speed with the laser emitting in the infrared spectral range. Utilization of the capacity of the combination laser machining machine is therefore generally poor. Separate laser machining machines have therefore prevailed for the machining of multilayer printed circuit boards.